Sample contact plate with latchable cover

ABSTRACT

Contact plates are provided including a base member and a lid. The base member has a sidewall extending circumferentially around a peripheral edge portion thereof to define a sample receiving area. The lid has a sidewall extending circumferentially around a peripheral edge portion thereof. A plurality of ribs extend from an inner surface of the sidewall of the lid. The ribs are configured to provide an interference fit engagement between the sidewall of the base member and the sidewall of the lid when the lid is attached to the base member.

This application is a continuation of application Ser. No. 10/178,422,filed June 24, 2002, now U.S. Pat. 6,602,704.

FIELD OF THE INVENTION

The present invention relates to devices for holding samples and, moreparticularly, to contact plates with lids for enclosing samples, such asmicroorganisms.

BACKGROUND OF THE INVENTION

A variety of sampling devices have been developed over the years forholding an agar media, or the like, in order to test whethermicroorganisms are present in a sample. One problem encountered withexisting sampling devices is that the person who is using the device mayhave difficulty handling the sampling device and the sample withoutintroducing contaminants that might affect the test.

Another difficulty associated with conventional sampling devices is thatit often becomes hard to remove a lid from a dish because of a moistureseal lock. However, the opposite problem, the lid being inadvertentlydetached or removed when it is desired to maintain the sampling devicein a covered state, may also be encountered with known sampling devices,which may adversely affect the ability to maintain, handle and/or storethe sampling devices.

U.S. Pat. No. 5,854,065 describes one known type of microorganismsampling device. A base member is provided with a continuous sidewallproviding a holding area for the agar media. A peripheral supportsurface extends around the base member at the external diameter of thebase member outside the continuous sidewall. The lid member of thesampling device has a flange extending around the external diameterthereof, which includes a plurality of lugs downwardly extendingtherefrom that contact the peripheral support surface of the base memberwhen the lid member is attached and define a gap allowing for airflowbetween the lid and base member to inhibit the creation of a moistureseal lock.

The count-tact Plate™ from bioMerieux, Inc. of France is a further typeof microorganism sampling device. The count-tact Plate™ includes a basemember with a continuous sidewall providing a holding area. The basemember sidewall includes a plurality of ribs extending from an outersurface thereof that are contacted by the lid of the count-tact Plate™when the lid is pressed onto the base member by a user. The ribs may,thus, operate to removably connect the lid to the base member.

SUMMARY OF THE INVENTION

According to embodiments of the present invention, contact plates areprovided including a base member and a lid. The base member has anupwardly extending sidewall extending circumferentially around aperipheral edge portion thereof to define a sample receiving area. Thelid has a sidewall extending circumferentially around a peripheral edgeportion thereof. A plurality of ribs extend inwardly from an innersurface of the sidewall of the lid. The ribs are configured to providean interference fit engagement between the sidewall of the base memberand the sidewall of the lid when the lid is attached to the base member.

In further embodiments of the present invention, the base memberincludes a contact surface extending around the sidewall of the basemember outside the sample receiving area. The lid includes a flangemember extending outwardly from a bottom end of the sidewall of the lidand positioned to engage the contact surface of the base member when thelid is attached to the base member. The contact surface of the basemember may also include a plurality of ribs extending upwardly therefromand positioned to engage the flange member of the lid when the lid isattached to the base member. The ribs of the base member and the ribs ofthe lid may together define an airflow passage to the sample receivingarea when the lid is attached to and secured to the base member.

In other embodiments of the present invention, the ribs of the lid areconfigured to provide a retention force of between about 50 grams andabout 2000 grams when the lid is attached to the base member and theflange member engages the contact surface of the base member. The ribsof the lid may be configured to provide a retention force of at leastabout 50 grams when the lid is attached to the base member and theflange member of the lid engages the contact surface of the base memberindependent of the rotational orientation of the lid relative to thebase member on repeated attaching of the lid to the base member.

In further embodiments of the present invention, the ribs of the lidtaper inwardly at a first angle relative to a central axis of thecontact plate. An outer surface of the sidewall of the base membertapers inwardly at a second angle relative to the central axis of thecontact plate. The first angle and the second angle are selected toprovide the interference fit engagement. The first angle may be betweenabout 3.5 degrees and about 4.5 degrees and the second angle may bebetween about 3.5 degrees and about 4.5 degrees.

In other embodiments of the present invention, the ribs of the lid havea height relative to the inner surface of the sidewall of the lid at abottom side of the lid of between about 0.02 centimeters (cm) and about0.04 cm. The ribs extending from an inner surface of the lid may have awidth of between about 0.04 centimeters (cm) and about 0.09 cm. Theinner surface of the lid may have a minimum radius about equal to amaximum radius of the outer surface of the sidewall of the base member.The inner surface of the lid may have a minimum radius within about 0.03cm of a maximum radius of the outer surface of the sidewall of the basemember.

In further embodiments of the present invention, the plurality of ribsextending from an inner surface of the lid includes at least 4 ribs. Insome embodiments, 4 ribs may be provided positioned about 90° apartaround the inner surface of the lid. In other embodiments at least 12ribs are provided. The at least 12 ribs may be positioned atsubstantially uniformly offset locations around the inner surface of thelid.

Objects of the present invention will be appreciated by those ofordinary skill in the art from a reading of the figures and the detaileddescription of the embodiments that follow, such description beingmerely illustrative of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which form a part of the specification,illustrate embodiments of the present invention. The drawings anddescription together serve to fully explain the invention. In thedrawings,

FIG. 1 is a perspective view of a contact plate in accordance withembodiments of the present invention;

FIG. 2 is a perspective view of a lid and a base member of a contactplate in accordance with embodiments of the present invention in an openposition;

FIG. 3 is a planar top view of a lid of a contact plate in accordancewith embodiments of the present invention;

FIG. 4 is a planar top view of a base member of a contact plate inaccordance with embodiments of the present invention;

FIG. 5 is a partial cross-sectional view of a lid and a base member of acontact plate in accordance with embodiments of the present invention inan open position; and

FIG. 6 is a partial cross-sectional view of the lid and a base member ofFIG. 5 in a closed position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, like numbers refer to like elements throughout. The terms“upwardly”, “downwardly”, “vertical”, “horizontal”, “bottom”, “top” andthe like are used herein for the purpose of explanation only and havethere normal orientation with reference to use of the contact plates insample testing.

Referring now to FIGS. 1-4, a contact plate in accordance withembodiments of the present invention will now be described. The contactplate 100 includes a lid 102 and a base member 104. The base member hasa sidewall 130 (FIG. 2) extending circumferentially around a peripheraledge portion of the base member 104. As seen in FIG. 2, the side wall130, in cooperation with the bottom wall (floor) 131, defines a samplereceiving area 135 in which a sample growth media, such as agar, and/orsamples to be evaluated may be contained. Preferably, a continuouslyextending side wall 130 is provided so that a growth media may be placedin the sample receiving area 135 in an agar form. The side wall 130includes an outer surface 134 and an inner surface 132.

The base member 104, as shown in FIG. 2, further includes a contactsurface 110 extending around the side wall 130 outside the samplereceiving area 135. A plurality of ribs 112 extend upwardly from thecontact surface 110 and are positioned to engage a flange member 108 ofthe lid 102 when the lid 102 is attached to the base member 104 asillustrated in FIG. 1. Also shown in FIG. 2 or FIG. 4 are numericalindicia 140, grid indicia 142 and alpha numeric indicia 144, all ofwhich may be used, for example, by reference to the grid indicia 142.

Lid 102 has a sidewall 106 extending circumferentially around aperipheral edge of the lid 102. A plurality of ribs 120 extend from aninner surface 122 (FIG. 3) of the side wall 106. The ribs 120 areconfigured to provide an interference fit engagement between the sidewall 130 of the base member 104 and the side wall 106 of the lid 102when the lid 102 is positioned and secured/attached to the base member104.

Referring now to the partial cross sectional views of FIGS. 5 and 6, acontact plate 200 according to embodiments of the present invention willbe further described. FIG. 5 shows a lid 202 and a base member 204 in anopen/unattached/unsecured position, while FIG. 6 shows the lid 202 andbase member 204 in a closed/secured/attached position with aninterference fit engagement holding the lid 202 coupled to the basemember 204. Like numbered features, of the 200 series, illustrated inFIGS. 5 and 6 correspond generally to the counterpart numbered featuresof the 100 series described with reference to FIGS. 1-4 above and willnot be further described herein.

As shown in FIGS. 5 and 6, by the cross-sectional view of the lid 202through one of the ribs 220 and the cross-sectional view of the basemember 204 through one of the ribs 212 on the contact surface 210 of thebase member 204, the ribs 220 have a height h extending inwardly from aninner surface 222 of the side wall 206. The ribs 120, 220 similarly havea width w as illustrated in FIG. 3. As shown in FIG. 5, the ribs 120,220 taper from a smaller height at a bottom end 255 of the lid 202 to agreater height at a top end 260 of the lid 202.

As shown in FIG. 6, the ribs 212 extending from the contact surface 210of the base member 204 and the ribs 220 extending from the inner surface222 of the lid 202 define an airflow passage 250 to the sample receivingarea 235 when the lid 202 is attached to the base member 204. As alsoshown in FIG. 6, an interference fit engagement region 265 is providedbetween the ribs 220 and the outer surface 234 (FIG. 5) of the sidewalls 230 (FIG. 5). The side walls 230 further include an inner surface232 defining the sample receiving area 235 with a single U-shaped wallmember providing the side wall 230. The sample receiving area 235 isfurther defined by the bottom wall 231 on which indicia, such as theindicia 140, 142, 144, may be provided.

As shown in FIG. 5, the outer surface 234 of the base side wall 230 maybe tapered at an angle θ′, tapering in from a maximum radius 275 of theouter surface 234 of the side wall 230 relative to a central axis A(FIG. 2) of the contact plate 100, 200. In addition, the ribs 220extending from the inner surface 222 of the lid 202 taper inwardly at anangle θ relative to the central axis A. The inner surface 222 of the lid202 has an associated minimum radius 270. The angle θ and the angle θ′may be selected to provide the desired interference fit engagementbetween the lid 202 and the base member 204 when the lid 202 ispositioned and secured in an attached position over the base member 204with the flange member 208 extending from the side wall 206 of the lid202 engaging the ribs 212 of the contact surface 210 of the base member204. In various embodiments, the resulting frictional retention force isbetween about 50 grams and about 2000 grams.

It is to be understood that the retention force may be affected by theangles θ, θ′, the height h of the ribs 220 and the minimum radius 270and maximum radius 275 of the lid 202 and the base member 204,respectively. It will be further understood that the frictional forcesproviding the interference fit engagement may be increased by increasingthe width w of the ribs 120, 220 as well as by one or more of increasingthe maximum radius 275 of the side walls 134, 234, by decreasing theminimum radius 270 of the side walls 106, 206, by increasing the heightH of the ribs 120, 220 or by changing the relative angles θ, θ′.

In particular embodiments of the present invention, the ribs 120, 220have a height h relative to the inner surface 122, 222 at the bottomside 255 of the lid 202 of between about 0.02 centimeters (cm) and about0.04 cm. The ribs 120, 220 may have a width of between about 0.04centimeters (cm) and about 0.09 centimeters (cm). The inner surface 122,222 of the lid 102, 202 may have a minimum radius within about 0.03 cmof a maximum radius of the outer surface 134, 234 of the side wall 130,230 of the base member 104, 204. The angle θ may be between about 3.5degrees and about 4.5 degrees and the angle θ′ may be between about 3.5degrees and about 4.5 degrees.

In various embodiments of the present invention, different numbers ofthe ribs 120, 220 may be provided on the lid 102, 202. In variousembodiments, there may be at least 4 ribs and at least 12 ribs, asillustrated by the 12 ribs shown for the embodiment illustrated in FIG.3. The ribs may be positioned at substantially uniformly spacedlocations around the inner surface 122, 222 of the side walls 106, 206of the lid 102, 202. For example, in a 4 rib embodiment, the ribs 120,220 may be positioned about 90 degrees apart around the inner surface122, 222 of the lid 102, 202.

The lid 102, 202 and the base member 104, 204 may both be molded fromthe same material or from different materials. In particular embodimentsof the present invention, the lid 102, 202 and the base member 104, 204are comprised of a material selected from the group consisting ofpolycarbonate and polystyrene. Preferably, the lid member 102, 202 andthe base member 104, 204 are molded from the same material.

Processes for molding lids 102, 202 and base members 104, 204 will beunderstood by those of skill in the art in light of the disclosureherein and will not be further described herein. However, it is to beunderstood that the side walls 106, 206 and the side walls 134, 234 aswell as other illustrated features of the contact plates 100, 200 may beprovided tapered angles selected to facilitate molding operations. Insuch configurations, it is to be understood that the reference anglesrelative to the axis A used for tapering of the features as describedherein may affect the interference force provided and, thus, thespecification of the height h with width w angles θ, θ′ and maximum andminimum radiuses of the engaging features are to be considered withreference to such angled aspects of the various members, which may beincluded to facilitate molding operations.

The inclusion of the ribs 120, 220 extending inwardly from the sidewalls 106, 206 of the lid 102, 202 as described herein may providepotential benefits in facilitating molding and maintenance of molds usedin manufacturing the contact plates 100, 200 of the present invention.For example, the selection of suitable inserts and other aspects of themold for the inventive contact plates 100, 200 may allow the use of afour cavity, rather than two cavity, mold.

The inventors of the present invention have observed in the prior artcontact plates that some deformation and creep may occur in the lid 102,202 over time when subjected to pressure. As a result, in applicationswhere the lid 102, 202 is removed and reinstalled over the base member104, 204 repeatedly, the rotational orientation of the lid 102, 202relative to the base member 104, 204 may change each time the lid 102,202 is replaced on the base member 104, 204 and the deformation of thelid may cause the retention force therebetween to change each time. Theinventors have found that the use of the ribs 120, 220 extending fromthe inner surface 122, 222 of the side walls 106,206 of the lid, ascontrasted with ribs on the base member, may beneficially provide aretention force of a desired minimum amount, such as of at least about50 grams, even on repeated pressing of the lid 102, 202 over the basemember 104, 204 independent of the rotational orientation of the lid102, 202 relative to the base member 104, 204.

Thus, a contact plate 100, 200 may be provided in accordance withembodiments of the present invention that provides a holding force tomaintain a lid in a closed position relative to a base member and theholding force may be maintained at a desirable level to insure properholding of the lid on the base member over repeated use, regardless ofthe rotational orientation used for the lid relative to the base member.Such benefits may be provided without otherwise changing the size and/orshape of the sample receiving area 135, 235 and the perception of thecontact plate 100, 200 by a user. As a result, the number of accidentalopenings and operator-related contamination events may be reduced usingan operator friendly one-touch closure with light pressure on the topcenter of the lid 102, 202.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. In the claims, means-plus-function clauses are intended tocover the structures described herein as performing the recited functionand not only structural equivalents but also equivalent structures.Therefore, it is to be understood that the foregoing is illustrative ofthe present invention and is not to be construed as limited to thespecific embodiments disclosed, and that modifications to the disclosedembodiments, as well as other embodiments, are intended to be includedwithin the scope of the appended claims. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

What is claimed is:
 1. A contact plate comprising: a base member havinga sidewall extending circumferentially around a peripheral edge portionthereof define a sample receiving area; and a lid having a sidewallextending circumferentially around a peripheral edge portion thereof anda plurality of ribs extending from an inner surface thereof, the ribsbeing configured to provide an interference fit engagement between thesidewall of the base member and the sidewall of the lid when the lid isattached to the base member; wherein the ribs extending from an innersurface of the lid taper inwardly at a first angle relative to a centralaxis of the contact plate and an outer surface of the sidewall of thebase member tapers inwardly at a second angle relative to the centralaxis of the contact plate.
 2. The contact plate of claim 1 wherein theribs extending from an inner surface of the lid have a height relativeto the inner surface of the sidewall of the lid at a bottom end of thelid of between about 0.02 centimeters (cm) and about 0.04 cm.
 3. Thecontact plate of claim 2 wherein the ribs extending from an innersurface of the lid have a width of between about 0.04 centimeters (cm)and about 0.09 cm.
 4. The contact plate of claim 2 wherein the innersurface of the lid has a minimum radius about equal to a maximum radiusof the outer surface of the sidewall of the base member.
 5. The contactplate of claim 2 wherein the surface of the lid has a minimum radiuswithin about 0.03 cm of a maximum radius of the outer surface of thesidewall of the base member.
 6. The contact plate of claim 2 wherein thefirst angle is between about 3.5 degrees and about 4.5 degrees and thesecond angle is between about 3.5 degrees and about 4.5 degrees.
 7. Thecontact plate of claim 2 wherein the plurality of ribs extending from aninner surface of the lid comprises at least 4 ribs.
 8. The contact plateof claim 7 wherein the plurality of ribs extending from an inner surfaceof the lid comprises 4 ribs positioned about 90° apart around the innersurface of the lid.
 9. The contact plate of claim 2 wherein theplurality of ribs extending from an inner surface of the lid comprisesat least 12 ribs.
 10. The contact plate of claim 9 wherein the at least12 ribs are positioned at substantially uniformly offset locationsaround the inner surface of the lid.
 11. The contact plate of claim 1wherein the first angle is between about 3.5 degrees and about 4.5degrees and the second angle is between about 3.5 degrees and about 4.5degrees.